Remove GLES2/WebGL1 support. (#821)

notable changes:

- depth/stencil images are now regular gl textures
- SG_PIXELFORMAT_DEPTH now resolves to GL_DEPTH_COMPONENT32F
- sg_gl_context_desc and sg_desc.gl removed
- in sg_begin_pass() only use glClearBuffer functions
- in sg_end_pass() MSAA resolve now does glInvalidateFramebuffer() on the MSAA buffer
- sg_features: instancing, multiple_render_targets, msaa_render_targets, imagetype_3d, imagetype_array removed
- sapp_desc.gl_force_gles2 removed
- sapp_gles2() function removed
- any GLES3-to-GLES2 fallbacks removed

1 files changed, 47 insertions, 44 deletions

diff --git a/util/sokol_debugtext.h b/util/sokol_debugtext.h
index 78ae60de..eed04361 100644
--- a/util/sokol_debugtext.h
+++ b/util/sokol_debugtext.h
@@ -18,7 +18,6 @@
     used by sokol_gfx.h and sokol_app.h):
 
     SOKOL_GLCORE33
-    SOKOL_GLES2
     SOKOL_GLES3
     SOKOL_D3D11
     SOKOL_METAL
@@ -2375,7 +2374,7 @@ static const uint8_t _sdtx_font_oric[2048] = {
 /*
     Embedded source code compiled with:
 
-    sokol-shdc -i debugtext.glsl -o debugtext.h -l glsl330:glsl100:hlsl4:metal_macos:metal_ios:metal_sim:wgpu -b
+    sokol-shdc -i debugtext.glsl -o debugtext.h -l glsl330:glsl300es:hlsl4:metal_macos:metal_ios:metal_sim:wgpu -b
 
     (not that for Metal and D3D11 byte code, sokol-shdc must be run
     on macOS and Windows)
@@ -2406,7 +2405,7 @@ static const uint8_t _sdtx_font_oric[2048] = {
         @program debugtext vs fs
 */
 #if defined(SOKOL_GLCORE33)
-static const char _sdtx_vs_src_glcore33[300] = {
+static const char _sdtx_vs_src_glsl330[300] = {
     0x23,0x76,0x65,0x72,0x73,0x69,0x6f,0x6e,0x20,0x33,0x33,0x30,0x0a,0x0a,0x6c,0x61,
     0x79,0x6f,0x75,0x74,0x28,0x6c,0x6f,0x63,0x61,0x74,0x69,0x6f,0x6e,0x20,0x3d,0x20,
     0x30,0x29,0x20,0x69,0x6e,0x20,0x76,0x65,0x63,0x32,0x20,0x70,0x6f,0x73,0x69,0x74,
@@ -2428,7 +2427,7 @@ static const char _sdtx_vs_src_glcore33[300] = {
     0x63,0x6f,0x6c,0x6f,0x72,0x30,0x3b,0x0a,0x7d,0x0a,0x0a,0x00,
 };
 
-static const char _sdtx_fs_src_glcore33[174] = {
+static const char _sdtx_fs_src_glsl330[174] = {
     0x23,0x76,0x65,0x72,0x73,0x69,0x6f,0x6e,0x20,0x33,0x33,0x30,0x0a,0x0a,0x75,0x6e,
     0x69,0x66,0x6f,0x72,0x6d,0x20,0x73,0x61,0x6d,0x70,0x6c,0x65,0x72,0x32,0x44,0x20,
     0x74,0x65,0x78,0x3b,0x0a,0x0a,0x6c,0x61,0x79,0x6f,0x75,0x74,0x28,0x6c,0x6f,0x63,
@@ -2441,41 +2440,45 @@ static const char _sdtx_fs_src_glcore33[174] = {
     0x72,0x65,0x28,0x74,0x65,0x78,0x2c,0x20,0x75,0x76,0x29,0x2e,0x78,0x78,0x78,0x78,
     0x20,0x2a,0x20,0x63,0x6f,0x6c,0x6f,0x72,0x3b,0x0a,0x7d,0x0a,0x0a,0x00,
 };
-#elif defined(SOKOL_GLES2) || defined(SOKOL_GLES3)
-static const char _sdtx_vs_src_gles2[266] = {
-    0x23,0x76,0x65,0x72,0x73,0x69,0x6f,0x6e,0x20,0x31,0x30,0x30,0x0a,0x0a,0x61,0x74,
-    0x74,0x72,0x69,0x62,0x75,0x74,0x65,0x20,0x76,0x65,0x63,0x32,0x20,0x70,0x6f,0x73,
-    0x69,0x74,0x69,0x6f,0x6e,0x3b,0x0a,0x76,0x61,0x72,0x79,0x69,0x6e,0x67,0x20,0x76,
-    0x65,0x63,0x32,0x20,0x75,0x76,0x3b,0x0a,0x61,0x74,0x74,0x72,0x69,0x62,0x75,0x74,
-    0x65,0x20,0x76,0x65,0x63,0x32,0x20,0x74,0x65,0x78,0x63,0x6f,0x6f,0x72,0x64,0x30,
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-    0x76,0x65,0x63,0x34,0x20,0x63,0x6f,0x6c,0x6f,0x72,0x30,0x3b,0x0a,0x0a,0x76,0x6f,
-    0x69,0x64,0x20,0x6d,0x61,0x69,0x6e,0x28,0x29,0x0a,0x7b,0x0a,0x20,0x20,0x20,0x20,
-    0x67,0x6c,0x5f,0x50,0x6f,0x73,0x69,0x74,0x69,0x6f,0x6e,0x20,0x3d,0x20,0x76,0x65,
-    0x63,0x34,0x28,0x28,0x70,0x6f,0x73,0x69,0x74,0x69,0x6f,0x6e,0x20,0x2a,0x20,0x76,
-    0x65,0x63,0x32,0x28,0x32,0x2e,0x30,0x2c,0x20,0x2d,0x32,0x2e,0x30,0x29,0x29,0x20,
-    0x2b,0x20,0x76,0x65,0x63,0x32,0x28,0x2d,0x31,0x2e,0x30,0x2c,0x20,0x31,0x2e,0x30,
-    0x29,0x2c,0x20,0x30,0x2e,0x30,0x2c,0x20,0x31,0x2e,0x30,0x29,0x3b,0x0a,0x20,0x20,
-    0x20,0x20,0x75,0x76,0x20,0x3d,0x20,0x74,0x65,0x78,0x63,0x6f,0x6f,0x72,0x64,0x30,
-    0x3b,0x0a,0x20,0x20,0x20,0x20,0x63,0x6f,0x6c,0x6f,0x72,0x20,0x3d,0x20,0x63,0x6f,
-    0x6c,0x6f,0x72,0x30,0x3b,0x0a,0x7d,0x0a,0x0a,0x00,
+#elif defined(SOKOL_GLES3)
+static const char _sdtx_vs_src_glsl300es[303] = {
+    0x23,0x76,0x65,0x72,0x73,0x69,0x6f,0x6e,0x20,0x33,0x30,0x30,0x20,0x65,0x73,0x0a,
+    0x0a,0x6c,0x61,0x79,0x6f,0x75,0x74,0x28,0x6c,0x6f,0x63,0x61,0x74,0x69,0x6f,0x6e,
+    0x20,0x3d,0x20,0x30,0x29,0x20,0x69,0x6e,0x20,0x76,0x65,0x63,0x32,0x20,0x70,0x6f,
+    0x73,0x69,0x74,0x69,0x6f,0x6e,0x3b,0x0a,0x6f,0x75,0x74,0x20,0x76,0x65,0x63,0x32,
+    0x20,0x75,0x76,0x3b,0x0a,0x6c,0x61,0x79,0x6f,0x75,0x74,0x28,0x6c,0x6f,0x63,0x61,
+    0x74,0x69,0x6f,0x6e,0x20,0x3d,0x20,0x31,0x29,0x20,0x69,0x6e,0x20,0x76,0x65,0x63,
+    0x32,0x20,0x74,0x65,0x78,0x63,0x6f,0x6f,0x72,0x64,0x30,0x3b,0x0a,0x6f,0x75,0x74,
+    0x20,0x76,0x65,0x63,0x34,0x20,0x63,0x6f,0x6c,0x6f,0x72,0x3b,0x0a,0x6c,0x61,0x79,
+    0x6f,0x75,0x74,0x28,0x6c,0x6f,0x63,0x61,0x74,0x69,0x6f,0x6e,0x20,0x3d,0x20,0x32,
+    0x29,0x20,0x69,0x6e,0x20,0x76,0x65,0x63,0x34,0x20,0x63,0x6f,0x6c,0x6f,0x72,0x30,
+    0x3b,0x0a,0x0a,0x76,0x6f,0x69,0x64,0x20,0x6d,0x61,0x69,0x6e,0x28,0x29,0x0a,0x7b,
+    0x0a,0x20,0x20,0x20,0x20,0x67,0x6c,0x5f,0x50,0x6f,0x73,0x69,0x74,0x69,0x6f,0x6e,
+    0x20,0x3d,0x20,0x76,0x65,0x63,0x34,0x28,0x28,0x70,0x6f,0x73,0x69,0x74,0x69,0x6f,
+    0x6e,0x20,0x2a,0x20,0x76,0x65,0x63,0x32,0x28,0x32,0x2e,0x30,0x2c,0x20,0x2d,0x32,
+    0x2e,0x30,0x29,0x29,0x20,0x2b,0x20,0x76,0x65,0x63,0x32,0x28,0x2d,0x31,0x2e,0x30,
+    0x2c,0x20,0x31,0x2e,0x30,0x29,0x2c,0x20,0x30,0x2e,0x30,0x2c,0x20,0x31,0x2e,0x30,
+    0x29,0x3b,0x0a,0x20,0x20,0x20,0x20,0x75,0x76,0x20,0x3d,0x20,0x74,0x65,0x78,0x63,
+    0x6f,0x6f,0x72,0x64,0x30,0x3b,0x0a,0x20,0x20,0x20,0x20,0x63,0x6f,0x6c,0x6f,0x72,
+    0x20,0x3d,0x20,0x63,0x6f,0x6c,0x6f,0x72,0x30,0x3b,0x0a,0x7d,0x0a,0x0a,0x00,
 };
-static const char _sdtx_fs_src_gles2[212] = {
-    0x23,0x76,0x65,0x72,0x73,0x69,0x6f,0x6e,0x20,0x31,0x30,0x30,0x0a,0x70,0x72,0x65,
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-    0x7d,0x0a,0x0a,0x00,
+static const char _sdtx_fs_src_glsl300es[247] = {
+    0x23,0x76,0x65,0x72,0x73,0x69,0x6f,0x6e,0x20,0x33,0x30,0x30,0x20,0x65,0x73,0x0a,
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+    0x29,0x20,0x6f,0x75,0x74,0x20,0x68,0x69,0x67,0x68,0x70,0x20,0x76,0x65,0x63,0x34,
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+    0x68,0x69,0x67,0x68,0x70,0x20,0x76,0x65,0x63,0x32,0x20,0x75,0x76,0x3b,0x0a,0x69,
+    0x6e,0x20,0x68,0x69,0x67,0x68,0x70,0x20,0x76,0x65,0x63,0x34,0x20,0x63,0x6f,0x6c,
+    0x6f,0x72,0x3b,0x0a,0x0a,0x76,0x6f,0x69,0x64,0x20,0x6d,0x61,0x69,0x6e,0x28,0x29,
+    0x0a,0x7b,0x0a,0x20,0x20,0x20,0x20,0x66,0x72,0x61,0x67,0x5f,0x63,0x6f,0x6c,0x6f,
+    0x72,0x20,0x3d,0x20,0x74,0x65,0x78,0x74,0x75,0x72,0x65,0x28,0x74,0x65,0x78,0x2c,
+    0x20,0x75,0x76,0x29,0x2e,0x78,0x78,0x78,0x78,0x20,0x2a,0x20,0x63,0x6f,0x6c,0x6f,
+    0x72,0x3b,0x0a,0x7d,0x0a,0x0a,0x00,
 };
 #elif defined(SOKOL_METAL)
 static const uint8_t _sdtx_vs_bytecode_metal_macos[2896] = {
@@ -3545,7 +3548,7 @@ static const uint8_t _sdtx_fs_bytecode_wgpu[940] = {
 static const char* _sdtx_vs_src_dummy = "";
 static const char* _sdtx_fs_src_dummy = "";
 #else
-#error "Please define one of SOKOL_GLCORE33, SOKOL_GLES2, SOKOL_GLES3, SOKOL_D3D11, SOKOL_METAL, SOKOL_WGPU or SOKOL_DUMMY_BACKEND!"
+#error "Please define one of SOKOL_GLCORE33, SOKOL_GLES3, SOKOL_D3D11, SOKOL_METAL, SOKOL_WGPU or SOKOL_DUMMY_BACKEND!"
 #endif
 
 // ███████ ████████ ██████  ██    ██  ██████ ████████ ███████
@@ -4035,11 +4038,11 @@ static void _sdtx_setup_common(void) {
     shd_desc.fs.images[0].image_type = SG_IMAGETYPE_2D;
     shd_desc.fs.images[0].sampler_type = SG_SAMPLERTYPE_FLOAT;
     #if defined(SOKOL_GLCORE33)
-        shd_desc.vs.source = _sdtx_vs_src_glcore33;
-        shd_desc.fs.source = _sdtx_fs_src_glcore33;
-    #elif defined(SOKOL_GLES2) || defined(SOKOL_GLES3)
-        shd_desc.vs.source = _sdtx_vs_src_gles2;
-        shd_desc.fs.source = _sdtx_fs_src_gles2;
+        shd_desc.vs.source = _sdtx_vs_src_glsl330;
+        shd_desc.fs.source = _sdtx_fs_src_glsl330;
+    #elif defined(SOKOL_GLES3)
+        shd_desc.vs.source = _sdtx_vs_src_glsl300es;
+        shd_desc.fs.source = _sdtx_fs_src_glsl300es;
     #elif defined(SOKOL_METAL)
         shd_desc.vs.entry = "main0";
         shd_desc.fs.entry = "main0";