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      1 /*
      2 * Copyright (C) 2011 The Android Open Source Project
      3 *
      4 * Licensed under the Apache License, Version 2.0 (the "License");
      5 * you may not use this file except in compliance with the License.
      6 * You may obtain a copy of the License at
      7 *
      8 * http://www.apache.org/licenses/LICENSE-2.0
      9 *
     10 * Unless required by applicable law or agreed to in writing, software
     11 * distributed under the License is distributed on an "AS IS" BASIS,
     12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13 * See the License for the specific language governing permissions and
     14 * limitations under the License.
     15 */
     16 #include "glUtils.h"
     17 #include <string.h>
     18 #include "ErrorLog.h"
     19 #include <IOStream.h>
     20 
     21 #include <GLES3/gl31.h>
     22 
     23 size_t glSizeof(GLenum type)
     24 {
     25     size_t retval = 0;
     26     switch(type) {
     27     case GL_BYTE:
     28     case GL_UNSIGNED_BYTE:
     29         retval = 1;
     30         break;
     31     case GL_SHORT:
     32     case GL_UNSIGNED_SHORT:
     33     case GL_HALF_FLOAT:
     34     case GL_HALF_FLOAT_OES:
     35         retval = 2;
     36         break;
     37     case GL_IMAGE_2D:
     38     case GL_IMAGE_3D:
     39     case GL_UNSIGNED_INT:
     40     case GL_INT:
     41     case GL_FLOAT:
     42     case GL_FIXED:
     43     case GL_BOOL:
     44         retval =  4;
     45         break;
     46 #ifdef GL_DOUBLE
     47     case GL_DOUBLE:
     48         retval = 8;
     49         break;
     50 #endif
     51     case GL_FLOAT_VEC2:
     52     case GL_INT_VEC2:
     53     case GL_UNSIGNED_INT_VEC2:
     54     case GL_BOOL_VEC2:
     55         retval = 8;
     56         break;
     57     case GL_INT_VEC3:
     58     case GL_UNSIGNED_INT_VEC3:
     59     case GL_BOOL_VEC3:
     60     case GL_FLOAT_VEC3:
     61         retval = 12;
     62         break;
     63     case GL_FLOAT_VEC4:
     64     case GL_BOOL_VEC4:
     65     case GL_INT_VEC4:
     66     case GL_UNSIGNED_INT_VEC4:
     67     case GL_FLOAT_MAT2:
     68         retval = 16;
     69         break;
     70     case GL_FLOAT_MAT3:
     71         retval = 36;
     72         break;
     73     case GL_FLOAT_MAT4:
     74         retval = 64;
     75         break;
     76     case GL_FLOAT_MAT2x3:
     77     case GL_FLOAT_MAT3x2:
     78         retval = 4 * 6;
     79         break;
     80     case GL_FLOAT_MAT2x4:
     81     case GL_FLOAT_MAT4x2:
     82         retval = 4 * 8;
     83         break;
     84     case GL_FLOAT_MAT3x4:
     85     case GL_FLOAT_MAT4x3:
     86         retval = 4 * 12;
     87         break;
     88     case GL_SAMPLER_2D:
     89     case GL_SAMPLER_3D:
     90     case GL_SAMPLER_CUBE:
     91         retval = 4;
     92         break;
     93     case GL_UNSIGNED_SHORT_4_4_4_4:
     94 	case GL_UNSIGNED_SHORT_5_5_5_1:
     95 	case GL_UNSIGNED_SHORT_5_6_5:
     96 	case GL_UNSIGNED_SHORT_4_4_4_4_REV_EXT:
     97 	case GL_UNSIGNED_SHORT_1_5_5_5_REV_EXT:
     98         retval = 2;
     99         break;
    100 	case GL_INT_2_10_10_10_REV:
    101 	case GL_UNSIGNED_INT_10F_11F_11F_REV:
    102 	case GL_UNSIGNED_INT_5_9_9_9_REV:
    103 	case GL_UNSIGNED_INT_2_10_10_10_REV:
    104 	case GL_UNSIGNED_INT_24_8_OES:;
    105         retval = 4;
    106         break;
    107 	case GL_FLOAT_32_UNSIGNED_INT_24_8_REV:
    108 		retval = 4 + 4;
    109         break;
    110     default:
    111         ALOGE("**** ERROR unknown type 0x%x (%s,%d)\n", type, __FUNCTION__,__LINE__);
    112         retval = 4;
    113     }
    114     return retval;
    115 
    116 }
    117 
    118 size_t glUtilsParamSize(GLenum param)
    119 {
    120     size_t s = 0;
    121 
    122     switch(param)
    123     {
    124     case GL_DEPTH_TEST:
    125     case GL_DEPTH_FUNC:
    126     case GL_DEPTH_BITS:
    127     case GL_MAX_CLIP_PLANES:
    128     case GL_GREEN_BITS:
    129     case GL_MAX_MODELVIEW_STACK_DEPTH:
    130     case GL_MAX_PROJECTION_STACK_DEPTH:
    131     case GL_MAX_TEXTURE_STACK_DEPTH:
    132     case GL_IMPLEMENTATION_COLOR_READ_FORMAT_OES:
    133     case GL_IMPLEMENTATION_COLOR_READ_TYPE_OES:
    134     case GL_NUM_COMPRESSED_TEXTURE_FORMATS:
    135     case GL_MAX_TEXTURE_SIZE:
    136     case GL_TEXTURE_GEN_MODE_OES:
    137     case GL_TEXTURE_ENV_MODE:
    138     case GL_FOG_MODE:
    139     case GL_FOG_DENSITY:
    140     case GL_FOG_START:
    141     case GL_FOG_END:
    142     case GL_SPOT_EXPONENT:
    143     case GL_CONSTANT_ATTENUATION:
    144     case GL_LINEAR_ATTENUATION:
    145     case GL_QUADRATIC_ATTENUATION:
    146     case GL_SHININESS:
    147     case GL_LIGHT_MODEL_TWO_SIDE:
    148     case GL_POINT_SIZE:
    149     case GL_POINT_SIZE_MIN:
    150     case GL_POINT_SIZE_MAX:
    151     case GL_POINT_FADE_THRESHOLD_SIZE:
    152     case GL_CULL_FACE:
    153     case GL_CULL_FACE_MODE:
    154     case GL_FRONT_FACE:
    155     case GL_SHADE_MODEL:
    156     case GL_DEPTH_WRITEMASK:
    157     case GL_DEPTH_CLEAR_VALUE:
    158     case GL_STENCIL_FAIL:
    159     case GL_STENCIL_PASS_DEPTH_FAIL:
    160     case GL_STENCIL_PASS_DEPTH_PASS:
    161     case GL_STENCIL_REF:
    162     case GL_STENCIL_WRITEMASK:
    163     case GL_MATRIX_MODE:
    164     case GL_MODELVIEW_STACK_DEPTH:
    165     case GL_PROJECTION_STACK_DEPTH:
    166     case GL_TEXTURE_STACK_DEPTH:
    167     case GL_ALPHA_TEST_FUNC:
    168     case GL_ALPHA_TEST_REF:
    169     case GL_ALPHA_TEST:
    170     case GL_DITHER:
    171     case GL_BLEND_DST:
    172     case GL_BLEND_SRC:
    173     case GL_BLEND:
    174     case GL_LOGIC_OP_MODE:
    175     case GL_SCISSOR_TEST:
    176     case GL_MAX_TEXTURE_UNITS:
    177     case GL_ACTIVE_TEXTURE:
    178     case GL_ALPHA_BITS:
    179     case GL_ARRAY_BUFFER_BINDING:
    180     case GL_BLUE_BITS:
    181     case GL_CLIENT_ACTIVE_TEXTURE:
    182     case GL_CLIP_PLANE0:
    183     case GL_CLIP_PLANE1:
    184     case GL_CLIP_PLANE2:
    185     case GL_CLIP_PLANE3:
    186     case GL_CLIP_PLANE4:
    187     case GL_CLIP_PLANE5:
    188     case GL_COLOR_ARRAY:
    189     case GL_COLOR_ARRAY_BUFFER_BINDING:
    190     case GL_COLOR_ARRAY_SIZE:
    191     case GL_COLOR_ARRAY_STRIDE:
    192     case GL_COLOR_ARRAY_TYPE:
    193     case GL_COLOR_LOGIC_OP:
    194     case GL_COLOR_MATERIAL:
    195     case GL_PACK_ALIGNMENT:
    196     case GL_PERSPECTIVE_CORRECTION_HINT:
    197     case GL_POINT_SIZE_ARRAY_BUFFER_BINDING_OES:
    198     case GL_POINT_SIZE_ARRAY_STRIDE_OES:
    199     case GL_POINT_SIZE_ARRAY_TYPE_OES:
    200     case GL_POINT_SMOOTH:
    201     case GL_POINT_SMOOTH_HINT:
    202     case GL_POINT_SPRITE_OES:
    203     case GL_COORD_REPLACE_OES:
    204     case GL_COMBINE_ALPHA:
    205     case GL_SRC0_RGB:
    206     case GL_SRC1_RGB:
    207     case GL_SRC2_RGB:
    208     case GL_OPERAND0_RGB:
    209     case GL_OPERAND1_RGB:
    210     case GL_OPERAND2_RGB:
    211     case GL_SRC0_ALPHA:
    212     case GL_SRC1_ALPHA:
    213     case GL_SRC2_ALPHA:
    214     case GL_OPERAND0_ALPHA:
    215     case GL_OPERAND1_ALPHA:
    216     case GL_OPERAND2_ALPHA:
    217     case GL_RGB_SCALE:
    218     case GL_ALPHA_SCALE:
    219     case GL_COMBINE_RGB:
    220     case GL_POLYGON_OFFSET_FACTOR:
    221     case GL_POLYGON_OFFSET_FILL:
    222     case GL_POLYGON_OFFSET_UNITS:
    223     case GL_RED_BITS:
    224     case GL_RESCALE_NORMAL:
    225     case GL_SAMPLE_ALPHA_TO_COVERAGE:
    226     case GL_SAMPLE_ALPHA_TO_ONE:
    227     case GL_SAMPLE_BUFFERS:
    228     case GL_SAMPLE_COVERAGE:
    229     case GL_SAMPLE_COVERAGE_INVERT:
    230     case GL_SAMPLE_COVERAGE_VALUE:
    231     case GL_SAMPLES:
    232     case GL_MAX_SAMPLES_EXT:
    233     case GL_STENCIL_BITS:
    234     case GL_STENCIL_CLEAR_VALUE:
    235     case GL_STENCIL_FUNC:
    236     case GL_STENCIL_TEST:
    237     case GL_STENCIL_VALUE_MASK:
    238     case GL_STENCIL_BACK_FUNC:
    239     case GL_STENCIL_BACK_VALUE_MASK:
    240     case GL_STENCIL_BACK_REF:
    241     case GL_STENCIL_BACK_FAIL:
    242     case GL_STENCIL_BACK_PASS_DEPTH_FAIL:
    243     case GL_STENCIL_BACK_PASS_DEPTH_PASS:
    244     case GL_STENCIL_BACK_WRITEMASK:
    245     case GL_TEXTURE_2D:
    246     case GL_TEXTURE_BINDING_2D:
    247     case GL_TEXTURE_BINDING_CUBE_MAP:
    248     case GL_TEXTURE_BINDING_EXTERNAL_OES:
    249     case GL_TEXTURE_COORD_ARRAY:
    250     case GL_TEXTURE_COORD_ARRAY_BUFFER_BINDING:
    251     case GL_TEXTURE_COORD_ARRAY_SIZE:
    252     case GL_TEXTURE_COORD_ARRAY_STRIDE:
    253     case GL_TEXTURE_COORD_ARRAY_TYPE:
    254     case GL_UNPACK_ALIGNMENT:
    255     case GL_VERTEX_ARRAY:
    256     case GL_VERTEX_ARRAY_BUFFER_BINDING:
    257     case GL_VERTEX_ARRAY_SIZE:
    258     case GL_VERTEX_ARRAY_STRIDE:
    259     case GL_VERTEX_ARRAY_TYPE:
    260     case GL_SPOT_CUTOFF:
    261     case GL_TEXTURE_MIN_FILTER:
    262     case GL_TEXTURE_MAG_FILTER:
    263     case GL_TEXTURE_WRAP_S:
    264     case GL_TEXTURE_WRAP_T:
    265     case GL_GENERATE_MIPMAP:
    266     case GL_GENERATE_MIPMAP_HINT:
    267     case GL_RENDERBUFFER_WIDTH_OES:
    268     case GL_RENDERBUFFER_HEIGHT_OES:
    269     case GL_RENDERBUFFER_INTERNAL_FORMAT_OES:
    270     case GL_RENDERBUFFER_RED_SIZE_OES:
    271     case GL_RENDERBUFFER_GREEN_SIZE_OES:
    272     case GL_RENDERBUFFER_BLUE_SIZE_OES:
    273     case GL_RENDERBUFFER_ALPHA_SIZE_OES:
    274     case GL_RENDERBUFFER_DEPTH_SIZE_OES:
    275     case GL_RENDERBUFFER_STENCIL_SIZE_OES:
    276     case GL_RENDERBUFFER_BINDING:
    277     case GL_FRAMEBUFFER_BINDING:
    278     case GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE_OES:
    279     case GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME_OES:
    280     case GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_LEVEL_OES:
    281     case GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_CUBE_MAP_FACE_OES:
    282     case GL_FENCE_STATUS_NV:
    283     case GL_FENCE_CONDITION_NV:
    284     case GL_TEXTURE_WIDTH_QCOM:
    285     case GL_TEXTURE_HEIGHT_QCOM:
    286     case GL_TEXTURE_DEPTH_QCOM:
    287     case GL_TEXTURE_INTERNAL_FORMAT_QCOM:
    288     case GL_TEXTURE_FORMAT_QCOM:
    289     case GL_TEXTURE_TYPE_QCOM:
    290     case GL_TEXTURE_IMAGE_VALID_QCOM:
    291     case GL_TEXTURE_NUM_LEVELS_QCOM:
    292     case GL_TEXTURE_TARGET_QCOM:
    293     case GL_TEXTURE_OBJECT_VALID_QCOM:
    294     case GL_BLEND_EQUATION_RGB_OES:
    295     case GL_BLEND_EQUATION_ALPHA_OES:
    296     case GL_BLEND_DST_RGB_OES:
    297     case GL_BLEND_SRC_RGB_OES:
    298     case GL_BLEND_DST_ALPHA_OES:
    299     case GL_BLEND_SRC_ALPHA_OES:
    300     case GL_MAX_LIGHTS:
    301     case GL_SHADER_TYPE:
    302     case GL_COMPILE_STATUS:
    303     case GL_SHADER_SOURCE_LENGTH:
    304     case GL_CURRENT_PROGRAM:
    305     case GL_SUBPIXEL_BITS:
    306     case GL_MAX_CUBE_MAP_TEXTURE_SIZE:
    307     case GL_NUM_SHADER_BINARY_FORMATS:
    308     case GL_SHADER_COMPILER:
    309     case GL_MAX_VERTEX_ATTRIBS:
    310     case GL_MAX_VERTEX_UNIFORM_VECTORS:
    311     case GL_MAX_VARYING_VECTORS:
    312     case GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS:
    313     case GL_MAX_VERTEX_TEXTURE_IMAGE_UNITS:
    314     case GL_MAX_FRAGMENT_UNIFORM_VECTORS:
    315     case GL_MAX_RENDERBUFFER_SIZE:
    316     case GL_MAX_TEXTURE_IMAGE_UNITS:
    317     case GL_REQUIRED_TEXTURE_IMAGE_UNITS_OES:
    318     case GL_FRAGMENT_SHADER_DERIVATIVE_HINT_OES:
    319     case GL_LINE_WIDTH:
    320     case GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_ATTRIBS:
    321     case GL_MAX_UNIFORM_BUFFER_BINDINGS:
    322     case GL_MAX_ATOMIC_COUNTER_BUFFER_BINDINGS:
    323     case GL_MAX_SHADER_STORAGE_BUFFER_BINDINGS:
    324     case GL_UNIFORM_BLOCK_BINDING:
    325     case GL_UNIFORM_BLOCK_DATA_SIZE:
    326     case GL_UNIFORM_BLOCK_NAME_LENGTH:
    327     case GL_UNIFORM_BLOCK_ACTIVE_UNIFORMS:
    328     case GL_UNIFORM_BLOCK_REFERENCED_BY_VERTEX_SHADER:
    329     case GL_UNIFORM_BLOCK_REFERENCED_BY_FRAGMENT_SHADER:
    330     case GL_CURRENT_QUERY:
    331     case GL_QUERY_RESULT:
    332     case GL_QUERY_RESULT_AVAILABLE:
    333     case GL_READ_BUFFER:
    334 
    335     case GL_ACTIVE_ATOMIC_COUNTER_BUFFERS:
    336     case GL_ACTIVE_ATTRIBUTES:
    337     case GL_ACTIVE_ATTRIBUTE_MAX_LENGTH:
    338     case GL_ACTIVE_UNIFORM_BLOCKS:
    339     case GL_ACTIVE_UNIFORM_BLOCK_MAX_NAME_LENGTH:
    340     case GL_ACTIVE_UNIFORMS:
    341     case GL_ACTIVE_UNIFORM_MAX_LENGTH:
    342     case GL_ATTACHED_SHADERS:
    343     case GL_DELETE_STATUS:
    344     case GL_INFO_LOG_LENGTH:
    345     case GL_LINK_STATUS:
    346     case GL_PROGRAM_BINARY_RETRIEVABLE_HINT:
    347     case GL_PROGRAM_SEPARABLE:
    348     case GL_TRANSFORM_FEEDBACK_BUFFER_MODE:
    349     case GL_TRANSFORM_FEEDBACK_VARYINGS:
    350     case GL_TRANSFORM_FEEDBACK_VARYING_MAX_LENGTH:
    351     case GL_VALIDATE_STATUS:
    352         s = 1;
    353         break;
    354     case GL_ALIASED_LINE_WIDTH_RANGE:
    355     case GL_ALIASED_POINT_SIZE_RANGE:
    356     case GL_DEPTH_RANGE:
    357     case GL_MAX_VIEWPORT_DIMS:
    358     case GL_SMOOTH_POINT_SIZE_RANGE:
    359     case GL_SMOOTH_LINE_WIDTH_RANGE:
    360     case GL_SAMPLE_POSITION:
    361         s= 2;
    362         break;
    363     case GL_SPOT_DIRECTION:
    364     case GL_POINT_DISTANCE_ATTENUATION:
    365     case GL_CURRENT_NORMAL:
    366     case GL_COMPUTE_WORK_GROUP_SIZE:
    367         s =  3;
    368         break;
    369     case GL_CURRENT_VERTEX_ATTRIB:
    370     case GL_CURRENT_TEXTURE_COORDS:
    371     case GL_CURRENT_COLOR:
    372     case GL_FOG_COLOR:
    373     case GL_AMBIENT:
    374     case GL_DIFFUSE:
    375     case GL_SPECULAR:
    376     case GL_EMISSION:
    377     case GL_POSITION:
    378     case GL_LIGHT_MODEL_AMBIENT:
    379     case GL_TEXTURE_ENV_COLOR:
    380     case GL_SCISSOR_BOX:
    381     case GL_VIEWPORT:
    382     case GL_TEXTURE_CROP_RECT_OES:
    383     case GL_COLOR_CLEAR_VALUE:
    384     case GL_COLOR_WRITEMASK:
    385     case GL_AMBIENT_AND_DIFFUSE:
    386     case GL_BLEND_COLOR:
    387         s =  4;
    388         break;
    389     case GL_MODELVIEW_MATRIX:
    390     case GL_PROJECTION_MATRIX:
    391     case GL_TEXTURE_MATRIX:
    392         s = 16;
    393     break;
    394     default:
    395         ERR("glUtilsParamSize: unknow param 0x%08x\n", param);
    396         s = 1; // assume 1
    397     }
    398     return s;
    399 }
    400 
    401 void glUtilsPackPointerData(unsigned char *dst, unsigned char *src,
    402                      int size, GLenum type, unsigned int stride,
    403                      unsigned int datalen)
    404 {
    405     unsigned int  vsize = size * glSizeof(type);
    406     switch (type) {
    407     case GL_INT_2_10_10_10_REV:
    408     case GL_UNSIGNED_INT_2_10_10_10_REV:
    409         vsize = vsize / 4;
    410         break;
    411     default:
    412         break;
    413     }
    414 
    415     if (stride == 0) stride = vsize;
    416 
    417     if (stride == vsize) {
    418         memcpy(dst, src, datalen);
    419     } else {
    420         for (unsigned int i = 0; i < datalen; i += vsize) {
    421             memcpy(dst, src, vsize);
    422             dst += vsize;
    423             src += stride;
    424         }
    425     }
    426 }
    427 
    428 void glUtilsWritePackPointerData(void* _stream, unsigned char *src,
    429                                  int size, GLenum type, unsigned int stride,
    430                                  unsigned int datalen)
    431 {
    432     IOStream* stream = reinterpret_cast<IOStream*>(_stream);
    433 
    434     unsigned int  vsize = size * glSizeof(type);
    435     if (stride == 0) stride = vsize;
    436 
    437     if (stride == vsize) {
    438         stream->writeFully(src, datalen);
    439     } else {
    440         for (unsigned int i = 0; i < datalen; i += vsize) {
    441             stream->writeFully(src, (size_t)vsize);
    442             src += stride;
    443         }
    444     }
    445 }
    446 
    447 int glUtilsPixelBitSize(GLenum format, GLenum type)
    448 {
    449     int components = 0;
    450     int componentsize = 0;
    451     int pixelsize = 0;
    452     switch(type) {
    453     case GL_BYTE:
    454     case GL_UNSIGNED_BYTE:
    455         componentsize = 8;
    456         break;
    457     case GL_SHORT:
    458     case GL_UNSIGNED_SHORT:
    459     case GL_UNSIGNED_SHORT_5_6_5:
    460     case GL_UNSIGNED_SHORT_4_4_4_4:
    461     case GL_UNSIGNED_SHORT_5_5_5_1:
    462     case GL_RGB565_OES:
    463     case GL_RGB5_A1_OES:
    464     case GL_RGBA4_OES:
    465         pixelsize = 16;
    466         break;
    467     case GL_INT:
    468     case GL_UNSIGNED_INT:
    469     case GL_FLOAT:
    470     case GL_FIXED:
    471     case GL_UNSIGNED_INT_24_8_OES:
    472         pixelsize = 32;
    473         break;
    474     default:
    475         ERR("glUtilsPixelBitSize: unknown pixel type - assuming pixel data 0\n");
    476         componentsize = 0;
    477     }
    478 
    479     if (pixelsize == 0) {
    480         switch(format) {
    481 #if 0
    482         case GL_RED:
    483         case GL_GREEN:
    484         case GL_BLUE:
    485 #endif
    486         case GL_ALPHA:
    487         case GL_LUMINANCE:
    488         case GL_DEPTH_COMPONENT:
    489         case GL_DEPTH_STENCIL_OES:
    490             components = 1;
    491             break;
    492         case GL_LUMINANCE_ALPHA:
    493             components = 2;
    494             break;
    495         case GL_RGB:
    496 #if 0
    497         case GL_BGR:
    498 #endif
    499             components = 3;
    500             break;
    501         case GL_RGBA:
    502         case GL_BGRA_EXT:
    503             components = 4;
    504             break;
    505         default:
    506             ERR("glUtilsPixelBitSize: unknown pixel format...\n");
    507             components = 0;
    508         }
    509         pixelsize = components * componentsize;
    510     }
    511 
    512     return pixelsize;
    513 }
    514 
    515 // pack a list of strings into one.
    516 void glUtilsPackStrings(char *ptr,  char **strings,  GLint *length, GLsizei count)
    517 {
    518     char *p = ptr;
    519     *p = '\0';
    520     for (int i = 0; i < count; i++) {
    521         int l=0;
    522         if (strings[i]!=NULL) {
    523             if (length == NULL || length[i] < 0) {
    524                 l = strlen(strings[i]);
    525                 strcat(p, strings[i]);
    526             } else {
    527                 l = length[i];
    528                 strncat(p, strings[i], l);
    529             }
    530         }
    531         p += l;
    532     }
    533 }
    534 
    535 // claculate the length of a list of strings
    536 int glUtilsCalcShaderSourceLen( char **strings,  GLint *length, GLsizei count)
    537 {
    538     int len = 0;
    539     for (int i = 0; i < count; i++) {
    540         int l;
    541         if (length == NULL || length[i] < 0) {
    542             l = strings[i]!=NULL ? strlen(strings[i]) : 0;
    543         } else {
    544             l = length[i];
    545         }
    546         len += l;
    547     }
    548     return len;
    549 
    550 }
    551 
    552 // helper to get GL_COLOR_ATTACHMENTn names
    553 GLenum glUtilsColorAttachmentName(int i) {
    554 #undef COLOR_ATTACHMENT_CASE
    555 #define COLOR_ATTACHMENT_CASE(i) \
    556     case i: \
    557         return GL_COLOR_ATTACHMENT##i; \
    558 
    559     switch (i) {
    560         COLOR_ATTACHMENT_CASE(0)
    561         COLOR_ATTACHMENT_CASE(1)
    562         COLOR_ATTACHMENT_CASE(2)
    563         COLOR_ATTACHMENT_CASE(3)
    564         COLOR_ATTACHMENT_CASE(4)
    565         COLOR_ATTACHMENT_CASE(5)
    566         COLOR_ATTACHMENT_CASE(6)
    567         COLOR_ATTACHMENT_CASE(7)
    568         COLOR_ATTACHMENT_CASE(8)
    569         COLOR_ATTACHMENT_CASE(9)
    570         COLOR_ATTACHMENT_CASE(10)
    571         COLOR_ATTACHMENT_CASE(11)
    572         COLOR_ATTACHMENT_CASE(12)
    573         COLOR_ATTACHMENT_CASE(13)
    574         COLOR_ATTACHMENT_CASE(14)
    575         COLOR_ATTACHMENT_CASE(15)
    576     }
    577     return GL_NONE;
    578 #undef COLOR_ATTACHMENT_CASE
    579 }
    580 
    581 int glUtilsColorAttachmentIndex(GLenum attachment) {
    582 #undef COLOR_ATTACHMENT_CASE
    583 #define COLOR_ATTACHMENT_CASE(i) \
    584     case GL_COLOR_ATTACHMENT##i: \
    585         return i; \
    586 
    587     switch (attachment) {
    588         COLOR_ATTACHMENT_CASE(0)
    589         COLOR_ATTACHMENT_CASE(1)
    590         COLOR_ATTACHMENT_CASE(2)
    591         COLOR_ATTACHMENT_CASE(3)
    592         COLOR_ATTACHMENT_CASE(4)
    593         COLOR_ATTACHMENT_CASE(5)
    594         COLOR_ATTACHMENT_CASE(6)
    595         COLOR_ATTACHMENT_CASE(7)
    596         COLOR_ATTACHMENT_CASE(8)
    597         COLOR_ATTACHMENT_CASE(9)
    598         COLOR_ATTACHMENT_CASE(10)
    599         COLOR_ATTACHMENT_CASE(11)
    600         COLOR_ATTACHMENT_CASE(12)
    601         COLOR_ATTACHMENT_CASE(13)
    602         COLOR_ATTACHMENT_CASE(14)
    603         COLOR_ATTACHMENT_CASE(15)
    604     }
    605     return -1;
    606 #undef COLOR_ATTACHMENT_CASE
    607 }
    608 
    609 struct glUtilsDrawArraysIndirectCommand {
    610     GLuint count;
    611     GLuint primCount;
    612     GLuint first;
    613     GLuint reserved;
    614 };
    615 
    616 struct glUtilsDrawElementsIndirectCommand {
    617     GLuint count;
    618     GLuint primCount;
    619     GLuint first;
    620     GLint baseVertex;
    621     GLuint reserved;
    622 };
    623 
    624 GLuint glUtilsIndirectStructSize(IndirectCommandType cmdType) {
    625     switch (cmdType) {
    626     case INDIRECT_COMMAND_DRAWARRAYS:
    627         return sizeof(glUtilsDrawArraysIndirectCommand);
    628     case INDIRECT_COMMAND_DRAWELEMENTS:
    629         return sizeof(glUtilsDrawElementsIndirectCommand);
    630     }
    631     return 4;
    632 }
    633