对不起，这需要一些解释。我试图让它变得尽可能简单。
我想做什么： 我正在想象高度场。高度字段可能包含多个补丁。贴片是一种较小的纹理，可以改变高度字段。
我正在使用OpenGL 4.0，主要是tesselation着色器。但是对于这个问题，这应该是无关紧要的。
什么是正常工作。 我有高度字段（没有补丁）的可视化工作。关于该问题的有趣部分是细分评估着色器和片段着色器。
tesselation评估着色器从高度字段采样器中获取每个顶点的高度。
layout(quads, fractional_odd_spacing, ccw) in;
out float onEdge;
out float teDistanceToMinHeight;
out vec4 tcPosition;
void main()
{
// bilinear interpolate: position
vec4 pos_a = mix(gl_in[0].gl_Position, gl_in[1].gl_Position, gl_TessCoord.x);
vec4 pos_b = mix(gl_in[3].gl_Position, gl_in[2].gl_Position, gl_TessCoord.x);
vec4 position = mix(pos_a, pos_b, gl_TessCoord.y);
// bilinear interpolate: hf texture coordinate
vec2 tex_a = mix(gl_in[0].gl_TexCoord[HFTexCoordID].xy, gl_in[1].gl_TexCoord[HFTexCoordID].xy, gl_TessCoord.x);
vec2 tex_b = mix(gl_in[3].gl_TexCoord[HFTexCoordID].xy, gl_in[2].gl_TexCoord[HFTexCoordID].xy, gl_TessCoord.x);
vec2 hfTexCoord = mix(tex_a, tex_b, gl_TessCoord.y);
float height = getHeightFieldHeight(hfTexCoord);
position.y = height;
//position.y = getHeightFieldHeightMin();
gl_Position = gl_ModelViewProjectionMatrix * position;
tcPosition = gl_Position;
gl_TexCoord[HFTexCoordID].xy = hfTexCoord;
// a vertex is on the edge of a patch if one of the tess coords is 0
onEdge = float((gl_TessCoord.x == 0 || gl_TessCoord.y == 0));
teDistanceToMinHeight = height - getHeightFieldHeightMin();
}
片段着色器使用属于手头片段的顶点的reative高度来访问1D高度palett纹理。请暂时忽略高度渐变。它用于计算法线。这完全没问题。
in float onEdge;
in float teDistanceToMinHeight;
in vec4 tcPosition;
out vec4 FragColor;
vec3
getHeightMapGradient(in vec2 ts_position,
in vec2 texel_offset)
{
vec3 x = vec3(2.0 * texel_offset.x, 0.0, getHeightFieldHeight(ts_position + vec2(texel_offset.x, 0.0))
- getHeightFieldHeight(ts_position - vec2(texel_offset.x, 0.0)));
vec3 y = vec3(0.0, 2.0 * texel_offset.y, getHeightFieldHeight(ts_position + vec2(0.0, texel_offset.y))
- getHeightFieldHeight(ts_position - vec2(0.0, texel_offset.y)));
return cross(x, y);
}
void main()
{
if(teDistanceToMinHeight < 0.00001){
// filter points near the zero position
discard;
}
// attributes
vec2 hfTexCoords = gl_TexCoord[HFTexCoordID].xy;
//float hfPaletteTexCoord = getHeightFieldHeight(hfTexCoords) / HeightFieldHeight;
float hfPaletteTexCoord = (texture(HeightField, hfTexCoords).r -HeightFieldLowering);
vec2 heightMapSize = vec2(textureSize(HeightField, 0).xy);
vec2 heightMapTexelSize = vec2(1.0) / vec2(heightMapSize);
// some standard colors
vec4 white = vec4(1);
vec4 yellow = vec4(1,1,0,1);
vec4 blue = vec4(0,0,1,1);
// get the color
FragColor = texture(HeightFieldPalette, hfPaletteTexCoord ); // use height field palette as color
if(onEdge > 0.9 && ShowOriginalGrid == 1 ){
FragColor = mix(FragColor, yellow, 0.5);
}
// shading
vec3 n = normalize(getHeightMapGradient(hfTexCoords, heightMapTexelSize).xzy);
vec3 l = vec3(1,1,0);
vec3 v = normalize(CameraPosition - tcPosition.xyz);
vec3 h = normalize(l + v);
float df= dot(n, l);
FragColor = (FragColor * (df * 0.5 + 0.5)) // diffuse
+ vec4(1) * pow(max(0.0, dot(n,h)), 60.0) // specular
+ 0.1; // ambient
}
在每个着色器之前包含以下代码。它主要包含所有统一和辅助函数。
#version 400 compatibility
// defines
#define HFTexCoordID 0
// environment
uniform ivec2 ScreenSize = ivec2(800,600);
uniform vec3 CameraPosition = vec3(0);
// tesselation
uniform float MaxEdgeLength = 4;
// height field
uniform float HeightFieldHeight = 1;
uniform float HeightFieldLowering = 0.2;
uniform sampler2D HeightField;
uniform sampler1D HeightFieldPalette;
// density map
uniform sampler2D DensityMap;
// patches
uniform sampler2D[20] Patches;
uniform int PatchesCount = 0;
uniform ivec2[20] PatchesPositions;
uniform float[20] PatchesHeights;
uniform ivec2[20] PatchesSizes;
// show options
uniform int ShowOriginalGrid = 0;
// functions
ivec2 getHFPosition(vec2 hfTexCoords){
return ivec2(textureSize(HeightField, 0).xy * hfTexCoords);
}
ivec2 getPatchSize(in int patchIndex){
return PatchesSizes[patchIndex];
//return textureSize(Patches[patchIndex], 0).xy;
}
vec2 toPatchCoords(in int patchIndex, in vec2 hfTexCoords){
ivec2 hfPosition = getHFPosition(hfTexCoords);
ivec2 patchStart = PatchesPositions[patchIndex];
ivec2 patchPos = hfPosition - patchStart;
//return textureSize(Patches[1], 0).xy;
return vec2(patchPos / getPatchSize(patchIndex));
}
float getPatchHeight(in int patchIndex, in vec2 hfTexCoords){
vec2 patchCoords = toPatchCoords(patchIndex, hfTexCoords);
// seams like the combination of the for loop with this
// texture access results in undefined behavior.
float relHeight = (texture(Patches[patchIndex], patchCoords).r -0.5);
return relHeight * PatchesHeights[patchIndex] * HeightFieldHeight;
}
float getPatchedHeight(in vec2 texCoords){
float patchesHeight = 0;
// working
//patchesHeight += getPatchHeight(0, texCoords);
//patchesHeight += getPatchHeight(1, texCoords);
//patchesHeight += getPatchHeight(2, texCoords);
// only works for i < 5 .
for(int i = 0; i < 6 && i < PatchesCount-1; i++){
patchesHeight += getPatchHeight(i, texCoords);
}
return patchesHeight;
}
float getHeightFieldHeight(in vec2 textureCoordinates){
float height = (texture(HeightField, textureCoordinates).r -HeightFieldLowering) * HeightFieldHeight;
height += getPatchedHeight(textureCoordinates);
return height;
}
float getHeightFieldHeightMin(){
return (-0.2 * HeightFieldHeight);
}
float getDensity(in vec2 coords){
return texture(DensityMap, coords).r;
}
问题
只要我不访问 Patches 制服，上面描述和粘贴的着色器都能正常工作。
uniform sampler2D[20] Patches;
sampler2D []背后的想法是有一种数组，而这个数组的每个纹理可能有不同的大小。我知道这个构造中的每一个都使用（在这种情况下）20个纹理单元。这种限制很好。
当我访问Patches uniform时，片段着色器仅输出黑色像素。我知道，曲面细分评估着色器工作正常，因为我可以看到高度字段中的山丘，而不是它的一部分。
我非常感谢任何建议。关于这个问题。
我知道我可以使用sampler2DArray，但是每个元素（纹理）必须具有相同的大小。但我需要补丁大小是灵活的。将补丁剪切成固定大小的纹理并在着色器中将它们重新组合在一起，这可能是另一种选择，但除非我真的需要，否则我不想实现这种组织开销。
信息日志
Visualization Lib
rary v2011.5.1142 [f32]
Jun 9 2011 - 11:36:25 - GCC compiler [RELEASE] [x32]
--- Environment ---
VL_LOGFILE_PATH <not present>
VL_DATA_PATH <not present>
VL_VERBOSITY_LEVEL = NORMAL
VL_CHECK_GL_STATES = YES
--- Global Settings ---
Log file = log.txt
Data path = ../data
Verbosity level = NORMAL
Check OpenGL States = YES
--- GLEW ---
GLEW version: 1.5.7
--- OpenGL Info ---
OpenGL version: 4.1.0 NVIDIA 260.19.21
OpenGL vendor: NVIDIA Corporation
OpenGL renderer: Quadro 6000/PCI/SSE2
OpenGL profile: Compatible
GLSL version: 4.10 NVIDIA via Cg compiler
Max texture size: 16384
Texture coords: 8
Texture conventional units: 4
Texture image units: 32
Anisotropic texture filter: YES, 16X
S3 Texture Compression: YES
Vertex Buffer Object: YES
Pixel Buffer Object: YES
Framebuffer Object: YES
Max vertex attributes: 16
Max varying floats: 60
Max fragment uniform components: 2048
Max vertex uniform components: 4096
Max elements vertices: 1048576
Max elements indices: 1048576
--- OpenGL Extensions ---
GL_ARB_blend_func_extended GL_ARB_color_buffer_float
GL_ARB_compatibility GL_ARB_copy_buffer
GL_ARB_depth_buffer_float GL_ARB_depth_clamp
GL_ARB_depth_texture GL_ARB_draw_buffers
GL_ARB_draw_buffers_blend GL_ARB_draw_indirect
GL_ARB_draw_elements_base_vertex GL_ARB_draw_instanced
GL_ARB_ES2_compatibility GL_ARB_explicit_attrib_location
GL_ARB_fragment_coord_conventions GL_ARB_fragment_program
GL_ARB_fragment_program_shadow GL_ARB_fragment_shader
GL_ARB_framebuffer_object GL_ARB_framebuffer_sRGB
GL_ARB_geometry_shader4 GL_ARB_get_program_binary
GL_ARB_gpu_shader5 GL_ARB_gpu_shader_fp64
GL_ARB_half_float_pixel GL_ARB_half_float_vertex
GL_ARB_imaging GL_ARB_instanced_arrays
GL_ARB_map_buffer_range GL_ARB_multisample
GL_ARB_multitexture GL_ARB_occlusion_query
GL_ARB_occlusion_query2 GL_ARB_pixel_buffer_object
GL_ARB_point_parameters GL_ARB_point_sprite
GL_ARB_provoking_vertex GL_ARB_robustness
GL_ARB_sample_shading GL_ARB_sampler_objects
GL_ARB_seamless_cube_map GL_ARB_separate_shader_objects
GL_ARB_shader_bit_encoding GL_ARB_shader_objects
GL_ARB_shader_precision GL_ARB_shader_subroutine
GL_ARB_shading_language_100 GL_ARB_shadow
GL_ARB_sync GL_ARB_tessellation_shader
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GL_ARB_texture_buffer_object_rgb32 GL_ARB_texture_compression
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GL_ARB_texture_env_add GL_ARB_texture_env_combine
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GL_ARB_texture_float GL_ARB_texture_gather
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GL_ARB_texture_rectangle GL_ARB_texture_rg
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GL_ARB_transform_feedback3 GL_ARB_transpose_matrix
GL_ARB_uniform_buffer_object GL_ARB_vertex_array_bgra
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GL_ARB_vertex_shader GL_ARB_vertex_type_2_10_10_10_rev
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GL_EXT_blend_subtract GL_EXT_compiled_vertex_array
GL_EXT_Cg_shader GL_EXT_depth_bounds_test
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GL_EXT_draw_instanced GL_EXT_draw_range_elements
GL_EXT_fog_coord GL_EXT_framebuffer_blit
GL_EXT_framebuffer_multisample GL_EXTX_framebuffer_mixed_formats
GL_EXT_framebuffer_object GL_EXT_framebuffer_sRGB
GL_EXT_geometry_shader4 GL_EXT_gpu_program_parameters
GL_EXT_gpu_shader4 GL_EXT_multi_draw_arrays
GL_EXT_packed_depth_stencil GL_EXT_packed_float
GL_EXT_packed_pixels GL_EXT_pixel_buffer_object
GL_EXT_point_parameters GL_EXT_provoking_vertex
GL_EXT_rescale_normal GL_EXT_secondary_color
GL_EXT_separate_shader_objects GL_EXT_separate_specular_color
GL_EXT_shader_image_load_store GL_EXT_shadow_funcs
GL_EXT_stencil_two_side GL_EXT_stencil_wrap
GL_EXT_texture3D GL_EXT_texture_array
GL_EXT_texture_buffer_object GL_EXT_texture_compression_latc
GL_EXT_texture_compression_rgtc GL_EXT_texture_compression_s3tc
GL_EXT_texture_cube_map GL_EXT_texture_edge_clamp
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GL_EXT_texture_filter_anisotropic GL_EXT_texture_integer
GL_EXT_texture_lod GL_EXT_texture_lod_bias
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GL_EXT_texture_shared_exponent GL_EXT_texture_sRGB
GL_EXT_texture_swizzle GL_EXT_timer_query
GL_EXT_transform_feedback2 GL_EXT_vertex_array
GL_EXT_vertex_array_bgra GL_EXT_vertex_attrib_64bit
GL_IBM_rasterpos_clip GL_IBM_texture_mirrored_repeat
GL_KTX_buffer_region GL_NV_blend_square
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GL_NV_fog_distance GL_NV_fragment_program
GL_NV_fragment_program_option GL_NV_fragment_program2
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GL_NV_gpu_program5 GL_NV_gpu_program_fp64
GL_NV_gpu_shader5 GL_NV_half_float
GL_NV_light_max_exponent GL_NV_multisample_coverage
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GL_NV_texture_barrier GL_NV_texture_compression_vtc
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GL_NV_texture_multisample GL_NV_texture_rectangle
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GL_NV_texture_shader3 GL_NV_transform_feedback
GL_NV_transform_feedback2 GL_NV_vdpau_interop
GL_NV_vertex_array_range GL_NV_vertex_array_range2
GL_NV_vertex_attrib_integer_64bit GL_NV_vertex_buffer_unified_memory
GL_NV_vertex_program GL_NV_vertex_program1_1
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GL_NV_vertex_program3 GL_NV_video_capture
GL_NVX_conditional_render GL_NVX_gpu_memory_info
GL_SGIS_generate_mipmap GL_SGIS_texture_lod
GL_SGIX_depth_texture GL_SGIX_shadow
GL_SUN_slice_accum
--- GLEW ---
GLEW version: 1.5.7
--- OpenGL Info ---
OpenGL version: 4.1.0 NVIDIA 260.19.21
OpenGL vendor: NVIDIA Corporation
OpenGL renderer: Quadro 6000/PCI/SSE2
OpenGL profile: Compatible
GLSL version: 4.10 NVIDIA via Cg compiler
Max texture size: 16384
Texture coords: 8
Texture conventional units: 4
Texture image units: 32
Anisotropic texture filter: YES, 16X
S3 Texture Compression: YES
Vertex Buffer Object: YES
Pixel Buffer Object: YES
Framebuffer Object: YES
Max vertex attributes: 16
Max varying floats: 60
Max fragment uniform components: 2048
Max vertex uniform components: 4096
Max elements vertices: 1048576
Max elements indices: 1048576
--- OpenGL Extensions ---
GL_ARB_blend_func_extended GL_ARB_color_buffer_float
GL_ARB_compatibility GL_ARB_copy_buffer
GL_ARB_depth_buffer_float GL_ARB_depth_clamp
GL_ARB_depth_texture GL_ARB_draw_buffers
GL_ARB_draw_buffers_blend GL_ARB_draw_indirect
GL_ARB_draw_elements_base_vertex GL_ARB_draw_instanced
GL_ARB_ES2_compatibility GL_ARB_explicit_attrib_location
GL_ARB_fragment_coord_conventions GL_ARB_fragment_program
GL_ARB_fragment_program_shadow GL_ARB_fragment_shader
GL_ARB_framebuffer_object GL_ARB_framebuffer_sRGB
GL_ARB_geometry_shader4 GL_ARB_get_program_binary
GL_ARB_gpu_shader5 GL_ARB_gpu_shader_fp64
GL_ARB_half_float_pixel GL_ARB_half_float_vertex
GL_ARB_imaging GL_ARB_instanced_arrays
GL_ARB_map_buffer_range GL_ARB_multisample
GL_ARB_multitexture GL_ARB_occlusion_query
GL_ARB_occlusion_query2 GL_ARB_pixel_buffer_object
GL_ARB_point_parameters GL_ARB_point_sprite
GL_ARB_provoking_vertex GL_ARB_robustness
GL_ARB_sample_shading GL_ARB_sampler_objects
GL_ARB_seamless_cube_map GL_ARB_separate_shader_objects
GL_ARB_shader_bit_encoding GL_ARB_shader_objects
GL_ARB_shader_precision GL_ARB_shader_subroutine
GL_ARB_shading_language_100 GL_ARB_shadow
GL_ARB_sync GL_ARB_tessellation_shader
GL_ARB_texture_border_clamp GL_ARB_texture_buffer_object
GL_ARB_texture_buffer_object_rgb32 GL_ARB_texture_compression
GL_ARB_texture_compression_bptc GL_ARB_texture_compression_rgtc
GL_ARB_texture_cube_map GL_ARB_texture_cube_map_array
GL_ARB_texture_env_add GL_ARB_texture_env_combine
GL_ARB_texture_env_crossbar GL_ARB_texture_env_dot3
GL_ARB_texture_float GL_ARB_texture_gather
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GL_ARB_texture_rectangle GL_ARB_texture_rg
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GL_ARB_transform_feedback3 GL_ARB_transpose_matrix
GL_ARB_uniform_buffer_object GL_ARB_vertex_array_bgra
GL_ARB_vertex_array_object GL_ARB_vertex_attrib_64bit
GL_ARB_vertex_buffer_object GL_ARB_vertex_program
GL_ARB_vertex_shader GL_ARB_vertex_type_2_10_10_10_rev
GL_ARB_viewport_array GL_ARB_window_pos
GL_ATI_draw_buffers GL_ATI_texture_float
GL_ATI_texture_mirror_once GL_S3_s3tc
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GL_EXT_bgra GL_EXT_bindable_uniform
GL_EXT_blend_color GL_EXT_blend_equation_separate
GL_EXT_blend_func_separate GL_EXT_blend_minmax
GL_EXT_blend_subtract GL_EXT_compiled_vertex_array
GL_EXT_Cg_shader GL_EXT_depth_bounds_test
GL_EXT_direct_state_access GL_EXT_draw_buffers2
GL_EXT_draw_instanced GL_EXT_draw_range_elements
GL_EXT_fog_coord GL_EXT_framebuffer_blit
GL_EXT_framebuffer_multisample GL_EXTX_framebuffer_mixed_formats
GL_EXT_framebuffer_object GL_EXT_framebuffer_sRGB
GL_EXT_geometry_shader4 GL_EXT_gpu_program_parameters
GL_EXT_gpu_shader4 GL_EXT_multi_draw_arrays
GL_EXT_packed_depth_stencil GL_EXT_packed_float
GL_EXT_packed_pixels GL_EXT_pixel_buffer_object
GL_EXT_point_parameters GL_EXT_provoking_vertex
GL_EXT_rescale_normal GL_EXT_secondary_color
GL_EXT_separate_shader_objects GL_EXT_separate_specular_color
GL_EXT_shader_image_load_store GL_EXT_shadow_funcs
GL_EXT_stencil_two_side GL_EXT_stencil_wrap
GL_EXT_texture3D GL_EXT_texture_array
GL_EXT_texture_buffer_object GL_EXT_texture_compression_latc
GL_EXT_texture_compression_rgtc GL_EXT_texture_compression_s3tc
GL_EXT_texture_cube_map GL_EXT_texture_edge_clamp
GL_EXT_texture_env_combine GL_EXT_texture_env_dot3
GL_EXT_texture_filter_anisotropic GL_EXT_texture_integer
GL_EXT_texture_lod GL_EXT_texture_lod_bias
GL_EXT_texture_mirror_clamp GL_EXT_texture_object
GL_EXT_texture_shared_exponent GL_EXT_texture_sRGB
GL_EXT_texture_swizzle GL_EXT_timer_query
GL_EXT_transform_feedback2 GL_EXT_vertex_array
GL_EXT_vertex_array_bgra GL_EXT_vertex_attrib_64bit
GL_IBM_rasterpos_clip GL_IBM_texture_mirrored_repeat
GL_KTX_buffer_region GL_NV_blend_square
GL_NV_conditional_render GL_NV_copy_depth_to_color
GL_NV_copy_image GL_NV_depth_buffer_float
GL_NV_depth_clamp GL_NV_explicit_multisample
GL_NV_fence GL_NV_float_buffer
GL_NV_fog_distance GL_NV_fragment_program
GL_NV_fragment_program_option GL_NV_fragment_program2
GL_NV_framebuffer_multisample_coverage GL_NV_geometry_shader4
GL_NV_gpu_program4 GL_NV_gpu_program4_1
GL_NV_gpu_program5 GL_NV_gpu_program_fp64
GL_NV_gpu_shader5 GL_NV_half_float
GL_NV_light_max_exponent GL_NV_multisample_coverage
GL_NV_multisample_filter_hint GL_NV_occlusion_query
GL_NV_packed_depth_stencil GL_NV_parameter_buffer_object
GL_NV_parameter_buffer_object2 GL_NV_pixel_data_range
GL_NV_point_sprite GL_NV_primitive_restart
GL_NV_register_combiners GL_NV_register_combiners2
GL_NV_shader_buffer_load GL_NV_texgen_reflection
GL_NV_texture_barrier GL_NV_texture_compression_vtc
GL_NV_texture_env_combine4 GL_NV_texture_expand_normal
GL_NV_texture_multisample GL_NV_texture_rectangle
GL_NV_texture_shader GL_NV_texture_shader2
GL_NV_texture_shader3 GL_NV_transform_feedback
GL_NV_transform_feedback2 GL_NV_vdpau_interop
GL_NV_vertex_array_range GL_NV_vertex_array_range2
GL_NV_vertex_attrib_integer_64bit GL_NV_vertex_buffer_unified_memory
GL_NV_vertex_program GL_NV_vertex_program1_1
GL_NV_vertex_program2 GL_NV_vertex_program2_option
GL_NV_vertex_program3 GL_NV_video_capture
GL_NVX_conditional_render GL_NVX_gpu_memory_info
GL_SGIS_generate_mipmap GL_SGIS_texture_lod
GL_SGIX_depth_texture GL_SGIX_shadow
GL_SUN_slice_accum
PatchesContainer::PatchesContainer: working dir: ./data/patches/pick_height_testing_png/
PatchesContainer::loadPatchesFromWorkingDir ignoring file = data/patches/pick_height_testing_png/.svn
Patch::initialize(): name = data/patches/pick_height_testing_png/patch01-position=20x20-maxHeight=1.0.png
width = 50
height = 50
depth = 0
format = IF_LUMINANCE
type = IT_UNSIGNED_BYTE
pitch = 50
bytealign = 1
Patch::initialize(): name = data/patches/pick_height_testing_png/patch02-position=20x2-maxHeight=1.5.png
width = 20
height = 20
depth = 0
format = IF_LUMINANCE
type = IT_UNSIGNED_BYTE
pitch = 20
bytealign = 1
Found matching densitymap ./data/density_maps/pick_height_testing_png.png
loading height field image
name = ./data/horizons/pick_height_testing.png
width = 200
height = 200
depth = 0
format = IF_LUMINANCE
type = IT_UNSIGNED_BYTE
pitch = 200
bytealign = 1
name = ./data/textures/tesselation_palette_blue_red.png
width = 300
height = 0
depth = 0
format = IF_RGB
type = IT_UNSIGNED_BYTE
pitch = 900
bytealign = 1
GL_MAX_TESS_EVALUATION_TEXTURE_IMAGE_UNITS: 32
答案 0 :(得分：5)
好吧，我可以看到一个问题：
均匀采样器2D [20]补丁;
我想出一个问题，猜测你的OpenGL 4.0级硬件无法在一个着色器阶段中使用超过16个纹理。如果您想验证这一点，请检查GL_MAX_TESS_EVALUATION_TEXTURE_IMAGE_UNITS;我敢打赌它是16岁。
此外，访问采样器阵列的规则非常严格（我打赌你打破它们）。在GLSL 4.00中，采样器阵列的索引必须是：
1：编译时常量表达式
2：解析为统一值的表达式。不是关键字中的uniform，而是基于编译时常量或统一值的表达式。它们不能基于从纹理，着色器阶段输入或任何类型中检索到的值。
这是合法的：
for(int i = 0; i < someUniform; i++)
{
texture(Patches[i], texCoord);
}
这不合法：
texture(Patches[positionOfSomeVertex * uniformScaleFactor], texCoord);
有一个原因为什么人们使用数组纹理而不是采样器数组。
Adendum：也许GLSL版本4.10规范的引用会有所帮助：
片段着色器表达式是 如果所有片段都动态均匀 评估它得到相同的结果 值。当涉及循环时，这个 指的是表达式的值 相同的循环迭代。什么时候 涉及的功能，这是指 来自同一个呼叫点的呼叫。
这同样为其他人定义 着色器阶段，基于 他们处理的每个实例数据。
请注意，常量表达式是 平凡的动态统一。它 遵循典型的循环计数器 基于这些也是动态的 均匀的。
您的表达式涉及基于不动态统一的条件分支。因此，使用的索引不是动态统一的。
“动态统一”的基本思想是这样的：给定相同的uniform值，我应该能够将任何作为着色器阶段输入传递，并且将从数组。您的代码不保证这一点。